Adsorbates Engineering on ZnO for Ultraviolet Light Activation–free Organic Photovoltaic Modules

Abstract

Ultraviolet (UV) light is typically needed to activate inverted organic photovoltaic (OPV) devices with zinc oxide (ZnO) as electron transporting layer (ETL) for enhanced efficiency. Given that UV light may cause the degradation of active layers and interfaces, and considering the absence of UV light in typical indoor lighting, addressing the need of UV light activation for ZnO becomes paramount. Herein, we report the engineering of adsorbates on ZnO could solve this issue by increasing the annealing temperature and changing the recipe of ZnO. Increasing the content of O 1s at binding energy of 531 eV on ZnO in X‐ray photoelectron spectroscopy would be beneficial to alleviate the need of UV light activation. For the (ZnO)PEIE (zinc acetate dihydrate (ZAH) and polyethylenimine ethoxylated (PEIE) dissolved in 2‐methoxyethanol, PEIE used to provide amine in the precursor), annealing at 180 °C would eliminated S‐shape in the current density‐voltage (J‐V) characteristics without UV light activation. For traditional recipe of (ZnO)EA (ZAH and ethanolamine dissolved in 2‐methoxyethanol, ethanolamine used to provide amine in the precursor), annealing at 320 °C following by additional 0.1 wt% aqueous PEIE modification could reach the similar effect to the (ZnO)PEIE. OPV modules (9.8 cm2) with 180 °C annealed (ZnO)PEIE as ETL showed high photovoltaic performance under light conditions without UV: VOC = 4.73 V JSC = 16.3 μA/cm2, FF = 67.9% and PCE = 18.2% under LED (2700 K) condition at 1000 lux (light intensity of 288 μW/cm2); VOC = 5.76 V JSC = 2.8 mA/cm2, FF = 72.1% and PCE = 14.8% tested under 1 sun with the UV filter (light intensity of 0.788 sun). These high efficiencies were achieved in the modules without the need for UV light activation.This article is protected by copyright. All rights reserved.